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Malaria mosquitoes are vectors of dangerous human diseases and a model system for investigations of chromosome evolution, heterochromatin organization, and nuclei architecture in the cells of the reproductive system. Investigations of nurse cells chromosomes are aimed at understanding of mechanisms that cause interspecies differences in the nuclear spatial organization in these cells. One of the most important tasks of this research is the undestanding of molecular organization of the chromosome regions that are attached to the nuclear envelope. In the present review, the recent achievements in this field of research are described and unsolved problems of the spatial chromosome organization are identified.

In the germarium of polytrophic ovarioles of Calliphora erythrocephala (Mg.) fly, four mitotic divisions of cystoblasts give rise to 16-cell germ-line cysts. One cell differentiates into an oocyte, while the remaining 15 cells become nurse cells. Concomitantly actin-rich ring canals are formed at the intercellular junctions. The present study considers a mutual arrangement of the ring canals formed after the second to fourth mitoses relative to the ring canal formed after the first mitotic division in different regions of the germarium and egg chambers. During the cyst formation and its movement to the posterior end of the germarium, the ring canals are displaced relative to one another, thereby giving different branching variants of the cyst. The pattern of cell interconnections becomes stable in germarium region 2b and does not change during the cyst movement along the ovariole despite the cyst polarizes and increases in size.